/* Copyright 2012 Mozilla Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import { error } from '../shared/util';

function fixMetadata(meta) {
  return meta.replace(/>\\376\\377([^<]+)/g, function(all, codes) {
    var bytes = codes.replace(/\\([0-3])([0-7])([0-7])/g,
                              function(code, d1, d2, d3) {
      return String.fromCharCode(d1 * 64 + d2 * 8 + d3 * 1);
    });
    var chars = '';
    for (var i = 0; i < bytes.length; i += 2) {
      var code = bytes.charCodeAt(i) * 256 + bytes.charCodeAt(i + 1);
      chars += (code >= 32 && code < 127 && code !== 60 && code !== 62 &&
        code !== 38) ? String.fromCharCode(code) :
        '&#x' + (0x10000 + code).toString(16).substring(1) + ';';
    }
    return '>' + chars;
  });
}

function Metadata(meta) {
  if (typeof meta === 'string') {
    // Ghostscript produces invalid metadata
    meta = fixMetadata(meta);

    var parser = new DOMParser();
    meta = parser.parseFromString(meta, 'application/xml');
  } else if (!(meta instanceof Document)) {
    error('Metadata: Invalid metadata object');
  }

  this.metaDocument = meta;
  this.metadata = Object.create(null);
  this.parse();
}

Metadata.prototype = {
  parse: function Metadata_parse() {
    var doc = this.metaDocument;
    var rdf = doc.documentElement;

    if (rdf.nodeName.toLowerCase() !== 'rdf:rdf') { // Wrapped in <xmpmeta>
      rdf = rdf.firstChild;
      while (rdf && rdf.nodeName.toLowerCase() !== 'rdf:rdf') {
        rdf = rdf.nextSibling;
      }
    }

    var nodeName = (rdf) ? rdf.nodeName.toLowerCase() : null;
    if (!rdf || nodeName !== 'rdf:rdf' || !rdf.hasChildNodes()) {
      return;
    }

    var children = rdf.childNodes, desc, entry, name, i, ii, length, iLength;
    for (i = 0, length = children.length; i < length; i++) {
      desc = children[i];
      if (desc.nodeName.toLowerCase() !== 'rdf:description') {
        continue;
      }

      for (ii = 0, iLength = desc.childNodes.length; ii < iLength; ii++) {
        if (desc.childNodes[ii].nodeName.toLowerCase() !== '#text') {
          entry = desc.childNodes[ii];
          name = entry.nodeName.toLowerCase();
          this.metadata[name] = entry.textContent.trim();
        }
      }
    }
  },

  get: function Metadata_get(name) {
    return this.metadata[name] || null;
  },

  has: function Metadata_has(name) {
    return typeof this.metadata[name] !== 'undefined';
  },
};

export {
  Metadata,
};
